To prevent the thread in the sloughing condition from being mixed into a winding package by providing a thread-cut sensor which detects the thread-cutting caused by a sloughing part of the thread being hooked by a pin gage and stops a winding machine.

An automatic winder 1 consists of an inlet part 2, an oiling device 3, a winding device 4, and an outlet part 5. A pin gage 13 of a sloughing detecting part 8 installed at the inlet part 2 becomes the obstacle for the traveling of the thread 10 to cause the sloughing part of the thread in the sloughing condition being hooked by the pin gage 13. Tension in the thread 10 on the downstream side of the pin gage 13 is remarkably increased and the thread 10 is cut. Then the cutting of the thread 10 is detected by a thread-cut sensor 17, and the detected signal is transmitted to a winding machine control device to stop the winding machine. The thread with sloughing is not wound into the winding package as it is and deterioration of the quality can be prevented.